Two thread chainstitch sewing machines with thread presentor



Feb. 18, 1964 v. J. SIGODA 3,121,413

TWO THREAD CHAINSTITCH SEWING MACHINES WITH THREAD PRESENTOR ll Sheets-Sheet 1 Filed May 20, 1960 IN V EN TOR.

Mar 0. 5/6004 BY 0? rra mfr Feb. 18, 1964 v. J. SIGODA 3,121,413 TWO THREAD CHAINSTITCH SEWING MACHINES WITH THREAD PRESENTOR Filed May 20, 1960 ll Sheets-Sheet 2 Z R I [3. E. o

o n q a W \fl'k/ 4 5\ 5 I G HI. 1 INVENTOR. 0 HM m, 35 b0 V/CFOIFJSIGODA Feb. 18, 1964 v. J. SIGODA 3,121,413

TWO THREAD CHAINSTITCH SEWING MACHINES WITH THREAD PRESENTOR Filed May 20, 1960 ll Sheets-Sheet 5 IN V EN TOR.

hero d- 3/6004 BY Feb. 18, 1964 SIGQDA 3,121,413

V. TWO THREAD CHAINSTITCH SEWING MACHINES WITH THREAD PRESENTOR Filed May 20, 1960 ll Sheets-Sheet 4 INVENTOR. V/cro d. 5/6004 BY I A rroe/v y Feb. 18, 1964 SIGODA 3,121,413

V. J. TWO THREAD CHAINSTITCH SEWING MACHINES WITH THREAD PRESENTOR Filed May 20. 1960 ll Sheets-Sheet 5 INVENTOR. V/cra J. 5/6004 Feb. 18, 1964 v. J. SIGODA 3,121,413

TWO THREAD CHAINSTITCH SEWING MACHINES WITH THREAD PRESENTOR Filed May 20, 1960 11 SheetQ- Sheet s IN VEN TOR. l lcro 8/6004 Feb. 18, 1964 SIGODA 3,121,413

V. J. TWO THREAD CHAINSTITCH SEWING MACHINES WITH THREAD PRESENTOR Filed May 20, 1960 ll Sheets-Sheet 7 1 "HHHIM O IN V EN TOR. I//c r0 9 J, SIGODA Feb. 18, 1964 v. J. SIGODA 3,121,413

TWO THREAD CHAINSTITCH SEWING MACHINES TH THREAD PRESENTOR Filed May 20, 1960 ll Sheets-Sheet 8 IN VEN TOR. VIC m J- slcom Feb. 18, 1964 v, J, 1 0 3,121,413

TWO THREAD CHAINSTITCH SEWING MACHINES WITH THREAD PRESENTOR Filed May 20, 1960 ll Sheets-Sheet 9 INVENTOR. Mar-0 4/. SIGOOA ,4 rrop/vey Feb. 18, 1964 SIGODA 3,121,413

V. J. TWO THREAD CHAINSTITCH SEWING MACHINES WITH THREAD PRESENTOR Filed May 20, 1960 ll Sheets-Sheet 10 INVENTOR. V cro/P d. 5/6004 Feb. 18, 1964 SIGODA 3,121,413

V- J. TWO THREAD CHAINSTITCH SEWING MACHINES WITH THREAD PRESENTOR Filed May 20, 1960 l1 Sheets-Sheet 11 INVENTOR. V/c m c/ $16004 United States Patent York Filed May 20, 1960, Ser. No. 30,682 23 Claims. (Cl. 112-200) This invention relates to sewing machines capable of producing two thread chainstitching of the Federal type 401 either singly or in conjunction with Federal types 504 or 505 overedge stitching simultaneously. It also relates to mechanisms for converting industrial ty'pe lockstitch sewing machines for the production of two thread chainstitching either singly or in conjunction with overedge stitching.

By utilizing a chainstitch under-looper which operates transversely to the line of feed behind the needle in conjunction with a novel underlooper thread presentor which is rocked along the line of feed, the heretofore critical operating relationship between the needle and the underlooper involved in the interception by the needle of the underlooper thread is made tar less sensitive, and the underlooper no longer need be in the region of the needle path during the interception of the underlooper thread. The presentor takes over and holds the underlooper thread triangle in position for needle interception and thus, it is now possible to shift the position of the underlooper so that it can begin its return stroke for its interception of the needle thread loop much sooner than in conventional machines, and accordingly can be moving at a greater velocity at the time of interception to effect more positive engagement of the needle loop. This new arrangement also makes it possible to use sewing machines having short needle-bar strokes and short, stubby needles, all of which contribute to more effective performance than is available from conventional machines at higher operating speeds.

Thus it is now possible to utilize such basically short needle-bar stroke machines as lockstitch machines for two thread chainstitching. The advantages of shorter needle bar strokes at higher speed are a reduction in the lubrication requirements because of the lesser amount of friction in the bearings and the consequent reduction in wear, and the considerably smaller inertia forces acting destructively on the needlebar operating mechanism. This means that higher operating speeds are now in sight for two thread chainstitching machines. One remarkable feature of the short stroke machine is the unexpected increase in the capacity of the machine for either heavier plies or more plies of material. For example, in a typical lockstitch machine having a short stroke of only 1%, inches, the clearance bet-ween the needle point and the needle-plate is /2 to of an inch. In the longest stroke two thread chainstitching machine commercially available (and one in which the increased stroke has been obtained only at the cost of a great reduction in operating speed), with a stroke of 1 /2 inches, there is only /2 clearance between the needle point and the needleplate. The standard version of this machine provides only inch clearance between the needle point and the needle-plate with a stroke of 1%; inches which is 764 of an inch more than that of the lockstitch machine mentioned. Long stroke 'versions of the lockst-itch machine have an increase of only of an inch and extra long stroked versions have an increase of only inch, both of which add the same amount to the clearance between the needle point and the needle-plate, and consequently' the capacity of the sewing machine.

The use of short, stubby needles increases the reliability of interception by the needle of the underlooper thread 3,121,413 Patented Feb. 18, 1964 at high operating speeds because of the inherent stiffness of short needles and the resultant resistance to deflection and whip caused by inertia forces and machine vibration at high operating speeds. One result of the arrangement is that the positioning of the eye of the needle with respect to the point is no longer critical and the spacing between the eye and the point can be much shorter. It is literally possible to use a loekstitch needle with a short point for chainstitching and this has heretofore been thought impractical. As a matter of fact, the short lockstitoh needle that can be used with this new arrangement may even be only one half as long as the standard two thread :chainstitching needle.

The mode of chainstitching operation disclosed herein also makes it possible to convert already existing lockstitch sewing machines for the production of two thread chainstitching at relatively low cost. The existing two thread ohainstitching sewing machines now available are more expensive in first cost than the ordinary lock stitch sewing machine. Since large numbers of lockstitch sewing machines are already in use, conversion of such lockstitch machines significantly increases their usefulness and otters economic advantages because of the reduction in capital investment and in storage requirements for two machines as against one converted machine, and the ready availability of either type of stitching, particularly when such conversion may be eitected at low cost.

One :feature is that the simple movement of the underlooper makes it possible to produce chainstitching with a converted lockstitch machine at the highest rate of speed of which the basic machine is capable and this may exceed the speed at which the lockstitch may be properly produced.

The novel thread presentor stabilizes the interceptions of both the needle and underlooper threads regardless of stitch length and of speed of stitch formation. It functions in several ways. It produces an underlooper thread triangle of good form and presents it in such aspect that positive interception is easily attained and thus the relationship of the needle and underlooper for this portion of the stitch formation is no longer critical. Portions of the presentor function sequentially to force the needle thread loop onto the body of the underlooper and subsequently to keep the needle thread loop out of the path of the descending needle to prevent the latter from attacking its own thread. The base line of the underlooper thread triangle Wrapped about the limbs of the presentor is used to force the needle thread into the needle groove to shift the needle thread loop to the rear of the needle to make a. better target for interception by the underlooper, and thus, the use of additional thread guards for this purpose is made unnecessary. The action of the presentor coupled with the more rapidly moving underlooper at the moment of interception makes for positive sequential interceptions and thus avoids skips which are destructive to good two thread interchanging. The entire action makes for easier chaining off of the threads.

When the invention is incorporated in an existing lock stitch machine, the drive for the underlooper thread presentor may be conveniently obtained from the operating shaft from which the lockstitch hook is removed in the conversion, and the drive for the underlooper may he obtained in either of two ways. When the converted ma chine is to be used solely for two thread chainstitching, an attachment may be added at the underside of the lockstitch hook gear drive box for providing mechanism for operating the underlooper.

Alternately, when the sewing machine has already been converted for the production of compound seams including overedge stitching in accordance with the disclosure 3 in patent application Serial No. 511,933, filed May 31, 1955, now Patent No. 2,973,731, the drive for the chainstitch underlooper may be obtained by combining the chainstitch underlooper with the overedge looper so that they travel in unison. The latter type of conversion results in dual stitching such as that shown, in the U.S. patent to Lutz, No. 2,249,615.

Other objects and features will in part be obvious and in part will be pointed out in the following description, it being understood that the invention may be incorporated into other sewing machines whether of the particular brand of manufacture or others, so long as the disclosed principles are compatible with the construction of such machines. It should therefore be further understood that the following description and the drawings are merely illustrative and should not be construed in a limiting sense.

In the accompanying drawings:

FIG. I is a front elevational view of an industrial type sewing machine representative of such widely used lockstitchv machines as the Singer 400, 451, 600 classes which had previosly been converted for the production of compound seams including overedge stitching and lockstitching, and which is now converted in accordance with the disclosure herein for the production of two thread chainstitching in lieu of the lockstitching in conjunction with the overedge stitching; and in which parts of the machine have been broken away to show power takeoff arrangements. for driving the attachments by which such conversions have been effected; this particular view showing one version in which the chainstitch underlooper is either an integral part of or is carried by the overedge underlooper, but also indicating in broken line the manner in which an additional mechanism may be mounted under the bed of the machine for operating the chainstitch underlooper independently of the overedge underlooper;

FIG. 2 is an end elevation of the significant portions of the converted machine of FIG. 1 further illustrating the version inwhich the chainstitch and overedge underloopers travel as a unit;

FIG. 3 is aplan View of the significant portion of the underside of the converted sewing machine of FIGS. 1- and 2;

FIGS. 4 and 5 are perspective views taken from the same end of the machine as in FIG. 2, showing the arrangement of the two underloopers, of the respective needles for each, and of the chainstitch needle, underlooper and thread presentor at two extremes of position;

FIG. 6 is a detail view in perspective showing the relationship of the chainstitch underlooper and the thread presentor, and the drive mechanism for operating the thread presentor and a form of thread take-up mechanism for the chainstitch underlooper;

FIG. 7 is a front elevational view of a portion of the mechanism illustrated FIG. 6, partly in section, showing the drive elements for the chainstitch thread presentor and thread take-up;

FIG. 8 is a detail View of a portion of the combined overedge and chainstitch underloopers and of the feeddog and feed-bar, showing their operating relationship;

FIG. 9 is a plan view of the bottom of asewing machine which has been converted for independent operation of the chainstitch underlooper, showing the drive mechanism therefor mounted in position on the underside of the lockstitch hook gear drive box;

FIG. 10 isa plan View of the top of the unmounted mechanism shown on the machine in FIG. 9, illustrating the operating relationship of the independently driven chainstitch underlooper and its thread presentor;

FIGS. 11 and 12 are respectively end and front elevations of the mechanism shown in FIG. 10;

FIG. 13 is a sectional view of the mechanism taken on line 13-13 of FIG. 12;

FIGS. 14 to 18 are sequential views, in perspective, s g the i teraction. of the chainstitch needle, underlooper and the thread presentor; and interchaining of the needle and underlooper threads, and the chaining off of such threads in a 4-01 type of stitching as performed by either of the converted machines disclosed herein; and

PEG. 19 is a view in perspective similar to FIG. 14 showing a modified form of the underlooper having both chainstitch and overedge limbs, and the manner in which the chainstitch limb cooperates with the chainstitch needle and the presentor to form two thread chainstitching in the work While simultaneously, the overedge limb cooperates with the auxiliary looper and overedge needle to overcast the edge of the work.

The Sewing Machine The sewing machine consists of a cloth-plate 1 from one end of which rises the standard 2 of a hollow bracketarm 3 overhanging the cloth-plate and terminating at its free end in a head 4. Rotatably journalled in the bracketarm 3 is a horizontally disposed main actuating shaft (not shown) carrying at one end a belt-pulley 5. Within the bracket-arm 3, the main shaft carries a peripherally grooved pulley (not shown) connected by a clip-belt 6 disposed within the arm-standard 2 to. a similarly grooved pulley 8 carried by one end of a hook and feed actuating shaft 9' rotating one-to-one with the main-shaft and disposed below the cloth-plate 1 in substantialy parallelism therewith.

Shaft 9 normally carries an internal gear at its other end, the gear being in mesh withpinion 11 which is attached to one end of a horiozntally disposed hook shaft 12. In the machine as originally built, the ratio of the internal gear and the pinion is such that the pinion rotates twice for each rotation of the gear. Shaft 12 normally carries at one end, the hook which cooperates with the needle 14 in the formation of lockstitching, but which is removed in this conversion for two thread chainstitching.

The work is advanced past the stitch-forming members by feed mechanism of well known construction. Such feed mechanism produces the usual four motions of the feed-bar 15 and the feed-dog 16 carried thereby, the latter, in conjunction with the resser-foot 18-, serving to advance the work to the stitch-forming elements.

The stitch-forming mechanism for the original lockstitching machine includes drive mechanism for the needle-bar 19 and for a thread take-up mechanism generally indicated as 20. The needle-bar drive mechanism includes a crank-disk carried by the end of the main actuating shaft, and the crank-disk has extending therefrom, a crank-pin which is connected by a link pivotally to the vertically reciprocating needle-bar 19. In the "ersion of the converted machine which produces only chainstitching, needle 14 is carried by needle-bar 19, but in the modification in which compound stitching is produced, an additional needle holder 21 is utilized to carry the overedge needle 22.

All sewing machines require thread tensioning and take-up devices for the proper formation of the stitching. These mechanisms are well known in the art and require no elaboration either in connection with the basic sewing machine or the subsequently described conversion.

Other details concerning the basic lockstitch sewing machine may be obtained by reference to Zonis Patent No. 2,267,581 of December 23, 1941.

Conversion of the Sewing Machine Conversion involves principally providing drive mechanisms for the chainstitch underlooper thread presentor and for the operation of the chainstitch underlooper. The provision of drive mechanism for the thread presentor is basic to both the single seam two thread chainstitch version and the compound chainstitch-overedge seam variety.

The thread presentor is driven as follows. The internal gear carried at the end of shaft 9 is replaced by a spur gear 24 which is the same size as pinion 11 and therefore now provides a one-to-one rotation of shaft 12. As best seen in FIG. 7, shaft 12 is journalled in bearings supported in bushing 25 which is mounted in a bore 26 in the machine bed casting on the underside of the clothplate 1. On the end of shaft 12 on which the hook is normally mounted, in replacement thereof, an eccentricblock 28 is secured. Block 28 carries an eccentric stud 29 mounted a selected distance from the center of rotation to provide the requisite amount of eccentricity for rocking the presentor carrying arm 30. Arm 30 is pivotally mounted on a stud shaft 31 supported in a bracket which is either clamped or otherwise fixed on one end of the bushing 25. Rocking of arm 30 is produced by link 32 which is pivotally connected to arm 30 by stud 34 journalied in one bushed end of link 32, and by eccentric stud 2? inserted in the bore of bearing 35 retained in the large end of link 32. At the upper end of arm 39, provision is made for adjustably mounting the underlooper thread presentor 36. It will be readily appreciated that for each rotation of shaft 9, there will now be produced one cycle of rocking forwardly and rearwardly of the presenter 06 in time with the reciprocation of the needle 14.

The Thread Presenter Thread presentor 36 has several distinct portions whose functions are more fully detailed in the section of this specification headed Operation of Chainstitching Elements.

It has a shank portion by which it is held clamped in arm 30 (see FIG. 7) and a thread manipulating portion joined thereto. The latter portion extends horizontally forward in the direction of the line of stitching (see FIGS. 14 and 15) and is fork shaped, having a left limb 36a and a right limb 36b. The right limb (see FIG. 16) forms a corner 360 with a downwardly extending vertical section 36d. The left limb (see FIG. 17) forms a corner 36c with a downwardly extending portion designated 36 Thread T ake-Up formation may be regulated, as desired. This thread U take-up arrangement is not essential to the proper operation of the device and may either be omitted or some other take-up arrangement may be employed.

Driving the Chainstitch Underlooper As mentioned, the chainstitch underlooper is driven transversely to the line of feed in the conversion. One simple way to obtain this required motion may be availed of in those machines which have already been converted for the production of the compound seam including overedge stitching. In the conversion described in the mentioned patent, the overedge underlooper is also operated transversely to the line of feed. The mechanism whereby this is accomplished is fully described in said patent and will be detailed only briefly here. Rotary motion obtained through a gear train is transformed to rocking motion of rockshaft 52 to which the arm which supports underlooper 51 is clamped. In the lockstitch-overedge modification, underlooper 51 consists of a downwardly depending shank, which is clamped in the arm held on rockshaft 52, from which projects an arcuately shaped limb 51a which extends leftwardly toward the needles to a junction from which a reversely projecting limb 511; extends rightwardly. Limb 51b is longitudinally pierced to provide a passageway for the overedge underlooper thread C. This conversion consists in providing a modilied form of the underlooper 51 which is fashioned with a third limb 51c either fastened to or integrally formed with and projecting downwardly and then transversely from the junction of limbs 51a and 51b in the same direction as limb 51b.

Dimensioning of this third limb, and the positioning of its point and of its internal longitudinal thread slot are dictated by the physical limitations of space and the required correlation with needle 14 for proper formation of the chainstitch but these are matters within the skill of the machine designer and require no further elaboration.

It is clear that as underlooper 51 is shifted laterally across the line of feed, that both thread carrying limbs 51b and 510 will be transported to the right to intercept the threads of their respective needles when those needles are in position below the work and under the needleplate 54.

This arrangement however ties the operation of the chainstitch underlooper irrevocably to the operation of the overedge underlooper. Hence the timing of the operation of the overedge underlooper affects the timing of the chainstitch underlooper operation and these are not always of optimum compatibility.

Accordingly, another arrangement has been provided for independent operation of the chainstitch underlooper which overcomes this limitation, and of course is what is necessary when the sewing machine has not already been converted for compound seaming according to the mentioned patent.

The Independent Drive for the Chainstitch Underlooper As manufactured, the machine is provided on the underside of the bed with a downwardly projecting box in which the meshed internal gear and pinion 11 normally operate in an oil bath, and this box is sealed at the bottom by a gasketed plate 61. When the internal gear is removed from shaft 9, and gear 24 is installed, an additional helical gear 62 is also mounted on shaft 9. This gear powers the underlooper drive mechanism which will now be described.

Plate 61 is replaced by a support casting 64 which has a flanged portion 65 which is physically a counterpart of plate 61 and casting 64 may accordingly be mounted in place of plate 61 on the bottom of box 6%). Casting 64 has a pair of upwardly projecting lugs 66 between which is pivotally mounted a rocker support bracket 68 in which a pair of gear shafts 59 and 70, for idler helical gears 71 and 72, may be journalled. This rocker bracket provides adjustment for proper meshing of the mating helical gears when the casting 64 is mounted on box 60 and permits compensation to be made for variations in the original machining of the bottom of box 60. Bracket 68 is adjustable about its mount by means of opposed set screws 73.

Casting 64 also has a downwardly projecting box portion 74, which is likewise sealed off on the bottom by a gasketed plate 75. Gear 72 projects into this box 74 to mesh with a mating helical gear 76 fast on cross-shaft 7 8 journalled in the sides of box 74. Shaft 78 carries at its external end an eccentric-block 79 which is provided with an off center projecting stud 84) which fits within the bore of a bearing inserted in the large end of a long pitman 81.

Casting 64 also has an outrigger arm 82 projecting upwardly, and when casting 64 is mounted in place, to- Ward the region in which the needle and underlooper inter act. Arm 82 terminates in an elongated bearing boss 84 which is journalled a cross-shaft 85 which is disposed parallel to shaft 73. Shaft 85 carries clamped thereto a rocker arm 86 which is pivotally connected by pitman 81 with eccentric-block 79 for rocking shaft 85. At its forward end, shaft 85 carries clamped thereto, a looper carrier 83 in which the chainstitch underlooper 89 may be adjustably fixed at the proper height. Hence as shaft 9 rotates, underlooper 89 is rocked across the line of feed in time with the endwise vertical reciprocation of needle 14 and the rocking of thread presentor 36 parallel to the line of feed.

' In the modification in which casting 64 is. used, the latter may also be provided with means for pivotally supporting presentor carrying arm 30. Hence the support on bushing 25 is not required. Casting 64- is. provided with an additional arm 90 which may be bored and split to provide a clamp in which support stud 34 may be retained.

Operation of the Chainstitching Elements Operation of the various mechanisms of the sewing machine converted in accordance with this disclosure, is timed so that the following sequence occurs. The functions have been related to approximate positions of rotation of the mainshaft, and the zero position has been assumed as being that at which the needle is at the very bottom of its reciprocation, at the instant just before it begins its ascent. It should be understood that the following is' merely representative of one mode of operation and that small variations in timing of the interceptions, of the feed action and of the various thread take-ups may contribute to optimum perforance with different threads, materials, thickness and numbers of plies and at various stitch lengths and operating speeds. It is assumed that the needle and underlooper threads have been properly inserted and that the thread take-ups and tensioning devices are suitably adjusted and operating properly.

At the initial point, then, the needle will be fully down, the underlooper 89 will already be in the course of its movement to the right (facing the machine as in FIG. 1), with velocity, to intercept the needle thread loop which has. not as yet been formed, and the presenter 36 will be disposed forwardly with both limbs about the blade of the needle, about to start its rearward movement. The needle thread take-up will be holding the thread taut and there will be no feed action. Since the needle is fully down, normally, when an underlooper thread triangle has already been formed about the limbs of presenter 36, the needle will be. through the work, the needle plate and deep within the underlooper thread triangle. However, since this is assumed to be the very start of stitching, there will be no underlooper thread triangle to be entered at this stage.

The mainshaft. rotates about twenty-five degrees, raising the needle about /3 inch above its lowest position. The needle thread take-up will be slackening off and the friction of the material will cause the slackening thread to form a loop about the eye of the needle which the underlooper will now be entering with desirable velocity. When the underlooper thread triangle has been formed in succeeding stitches, the base line of the triangle held on the limbs of the rearwardly moving presenter 36 will be urged against the front of the needle, forcing the needle thread into its vertical groove, and the needle thread loop will bow out at the rear of the needle making underlooper interception more positive.

As the mainshaft rotates from this twenty-five degree point. until it reaches the ninety-five degree position, the needle will rise through the work until it reaches a point about A above the surface of the work. If the machine is also converted for compound stitching according to said patent, since the overedging attachment is mounted on a base plate which raises it A; inch above the surface of the bed of the machine, in such case, the needle will be just in line with the top of the work on the surface of the needle-plate mounted in the base plate of the overedging attachment. During this interval, the underlooper will continue to the right, and the needle thread loop now on the underlooper will come into contact with the right rise of the bump 91 on. the underlooper, and since the take-up is now pulling slightly on the needle thread, the bump on the underlooper will tend to push the needle thread loop to the right as the underlooper moves. However, the inner side of limb 36b of the presentor is in position, to retain both the front and back limbs of the needle thread loop from moving to the right initially, and as the presenter continues to move rearwardly, only the back limb of the needle thread loop, as bump 91 is forced through the needle thread loop. This retention of the needle thread loop lessens the amount of needle thread required during stitch formation. Since less thread is involved, less takeup action is required and less frictional wear is experienced by the thread, contributing to better high speed performance.

As the one hundred forty degree position of the mainshaft is reached, the needle is still moving upwardly, well above the Work, and the feed-dog is now coming up to clamp the Work against the sole of the presser foot just prior to feeding the work rearwardly which will continue until about the two hundred twenty five degree position. The underlooper is now at its extreme rightward position, and the presentor is at its rearward position, with the ends of'both of its limbs 35a and 36b just behind the underlooper clear of the needle thread loop. The needle thread take-up action has now tightened the needle thread about the underlooper body to the left of bump 91.

Between the one hundred forty degree point and the one hundred eighty degree position of the mainshaft, the needle is rising to the highest point of its reciprocation, the needle thread take-up action is drawing the needle thread tight, and the feed action is just about to become effective. The underlooper is now moving to the left, the bump 91 pushing the needle thread loop leftwardly with it. The presentor is now moving forwardly and the front end of limb 36b is entering under the underlooper thread leading from the eye of the underlooper, still disposed to the right well past the axis of needle reciprocation, to the needle slot above and to the rear to which the underlooper thread has been drawn either initially by hand, under the presser foot to start the stitch, or by its anchorage in the Work which had previously been fed rearwardly on the preceding stitch.

As the one hundred eighty degree position is reached, the needle is at its highest position, the thread take-up action is drawing the needle thread so that it is tight about the underlooper and the feed action is still in process. Since the underlooper is now moving leftwardly, the needle thread loop must climb the left rise of the bump 91 to be shed. As presentor 36 moves forwardly, the left side of limb 36a engages the right side of the needle thread loop which has been carried to the left by bump 91 as the underlooper moves in that direction, to hold the needle thread loop from subsequent movement into the path of needle reciprocation, and limb 36b continues under the underlooper thread over the body of the underlooper.

As the rotation of the mainshaft continues to about the two hundred fifteen or twenty degree position, the needle descends until it is about to /2 inch above the needleplate and the needle thread take-up action tightens the thread. The underlooper will still be moving to the left to shed the needle thread loop as it passes 01f bump 91. The presentor is still moving forwardly, and now the right side of limb 36b is retaining the underlooper thread as the underlooper moves to the left past the presentor. The left side of limb 36a retains the shed needle thread loop, now wrapped about the underlooper thread, from moving into the path of needle reciprocation.

As the two hundred fifty to sixty degree position is reached, the needle has descended so that now it is only about A; to inch above the needle-plate (in the compound seam version, just about in the work). The takeup is rapidly tightening up the needle thread but since the shedding of the needle thread loop releases some excess thread, the action has not yet fully taken up all the slack. The feed action has been completed. The underlooper is still moving leftwardly and presenter 36 is moving forwardly, and as it does, corner 360 at the junction of limb 36b and the vertical section 36d, engages the underlooper thread.

About twenty degrees of rotation later, the needle will have descended until it is either in the needle-plate of the compound seaming version or at the surface of the work in the plain chainstitching version. The take-up will be tightening the needle thread loop about the underlooper thread and the underlooper will be moving leftwardly, almost at the end of its stroke. The presentor 35 will be moving forwardly, and as it does, corner 362 at the junction of the limb 36a and the downwardly projecting edge 36 will engage the underlooper thread to form the base line of the underlooper thread triangle x, y and z, as shown in FIG. 15, and as the presentor continues forwardly, this base line will be carried past the axis of needle reciprocation.

At the two hundred ninety-five degree position, the needle will have descended through the work to just enter the underlooper thread triangle. The underlooper will now be at its extreme left position and the presenter at its most forward position with the underlooper thread triangle fully formed with its apex inclined upwardly. As the take-up action tightens the needle thread loop about the underlooper thread, this forms the anchorage for the left side of the triangle, the right side being anchored above in the Work. The tightening needle thread loop is maintained to the left out of the path of the needle by the left side of limb 36a of the presenter.

As the mainshaft rotates to the three hundred sixty degree position, the needle reaches its lowest point, within the underlooper thread triangle. The underlooper is already in the course of its movement to the right for the next needle thread loop interception and is picking up velocity. The presenter is moving backwardly carrying the base line of the thread triangle wrapped about its limbs, and as it carries this underlooper thread rearwardly, the latter forces the needle thread into its groove in the front of tie needle and this forms a thread loop at the rear of the needle which is ideally shaped for good interception by the rapidly approaching underlooper point.

Operation of the Combined Stitching Mechanisms When the two thread chainstitching mechanism described herein is added to a lockstitch sewing machine which has previously been converted for the production of dual seams including an overedge seam, one form that such modification may take is shown in FIGS. 1 to 6 and 8. In that version, the original overedge underlooper is replaced by a combined underlooper member 51 which has an added portion 51c which functions as the two thread chainstitch underlooper, In such instance, the operation of the added chainstitch underlooper portion is closely related to the operation of the overedge underlooper portion although the cooperation of the chainstitch elements proceeds substantially as previously explained.

The formation of the overedge stitching, which is more fully detailed in the mentioned patent involves the sequential interaction of needle 22, overedge underlooper limb 51b and the thread carrying auxiliary overedge looper 53 indicated in FIG. 19 and shown in FIG. 1.

The thread of overedge needle 22 forms into loops on the undersurface of the Work in the same manner and at the same time that the thread of needle 14 forms into loops on the undersurface of the work. Limb 51b intercepts the loops of needle 22 and limb Sic intercepts the loops of needle 14 in the movement rightwardly of underlooper 51. As the thread carried by limb 51b is being intercepted by the upwardly moving auxiliary looper, presenter 36 moves forwardly to intercept the thread carried by limb 51c to form the chainstitch looper thread triangle.

Meanwhile, the auxiliary looper passes upwardly over the edge of the work into the path of needle 22. As needle 22 descends and intercepts the thread carried by the auxiliary looper, needle 14 descends and enters the looper thread triang e wrapped about the limbs of pre- 1h sentor 36 which has concurrently carried the base line of the thread triangle forwardly of the path of needle 14.

These sequential needle, presenter, underlooper and auxiliary looper movements complete the two diflferent stitch formations simultaneously.

While preferred embodiments of the invention have been described in considerable detail and certain modiiications suggested, it will be understood that various other changes may be made in the several parts Without departing from the general principles and the scope of the invention is therefore defined by the appended claims.

What is claimed is:

1. In a two thread chainstitch sewing machine having a threaded needle which moves on an ascending and descending path to form needle thread loops, :1 bi-directionally moving threaded underlooper which intercepts said needle thread loops and in which the needle subsequently intercepts the underlooper thread, in sequence, to form chainstitching and operating mechanism for moving said needle and underlooper on their respective paths; the combination with a presentor member cooperating with said needle and said underlooper in the formation of chainstitching, mechanism associated with said needle and underlooper operating mechanism for moving said presenter on a bi-directionai path which intercepts the paths of movement of said needle and said underlooper, said presentor having a pair of spaced limbs which are disposed at either side of the path of movement of the needle, said limbs being adapted to intercept the underlooper thread to form the base line of a thread triangle as said presentor moves in one direction, said limbs having portions adapted to retain said base line of underlocper thread to transport the latter bodily from one side of the path of needle movement to the other for interception by the descending needle.

2. A sewing machine in accordance with claim 1 in which the limbs of said presentor member have portions adapted to progressively engage the thread of a needle thread loop previously intercepted by the underlooper to retain said thread out of the path of movement of said needle, as said presenter moves in opposite directions.

3. A presentor member for use in a two thread chainstitch sewing machine having a threaded needle which moves on an ascending and descending path to form needle thread loops, :1 bi-directionally moving threaded underlooper which intercepts said needle thread loops and in which the needle subsequently intercepts the underlooper thread, in sequence, to form chainstitching, and in which said presentor cooperates in the formation of the chainstitching and moves on a ei-directional path transverse to the path of the underlooper; said presentor having a pair of spaced limbs between which the needle may move on its path to intercept the underlooper thread; one of said limbs having a horizontally disposed edge adapted to engage the thread leading to a needle thread loop after interception by the underlooper to assist said intercepted needle thread loop to pass along the body of the underlooper as the presenter moves in one direction; and another horizontally disposed edge adapted to intercept and retain thereon the underlooper thread as said presentor moves in its other direction; and the other of said limbs having a horizontally disposed edge adapted to progressively engage and retain said intercepted needle thread loop out of the path of the descending needle and to engage and retain the underlooper thread on said limb to form with the portion of the underlooper thread retained on the first limb, the base line of an underlooper thread triangle, as said presentor moves in its second direction to present said intercepted underlooper thread to the descending needle for interception thereby; both of said limbs being adapted to retain said underlooper thread base line for subsequent pressing against the thread carried by said needle to form a needle thread loop better adapted for subsequent interception by the under- 1 l. looper, as said presentor again moves in its first direction.

4. In a sewing machine having a threaded needle which moves on an ascending and descending path to form needle thread loops, and bidirectionally moving underlooper which passes on only one side of the needle path and which intercepts the needle thread loops, said underlooper having an eye near its point through which a thread passes and which thread is in turn formed into a triangle for entry therein by the needle in the formation of two thread chainstitching: the combination with means for ensuring formation of the underlooper thread triangle independently of the position of the eye of the underlooper with respect to the needle path, comprising one element adapted to intercept and retain the underlooper thread and positioned to move across the line of passage of the underlooper at one side of the needle path; another element adapted to intercept and retain the same thread and positioned to move across the line of passage of the underlooper at the opposite side of the needle path to form the base line of the underlooper thread triangle, and operating means for moving said elements and the underlooper thread base line retained thereon across the line of passage of the underlooper to the side of the needle path opposite the line of the underlooper passage to complete the formation of the underlooper thread triangle for subsequent entry therein by the descending needle.

5. A sewing machine in accordance with claim 4 in which said elements in moving in the opposite direction cause the transported base line of underlooper thread to bear against the thread carried by said needle to force the formation of the needle thread loop at the opposite side of the needle in better form for subsequent interception by the underlooper.

6. A sewing machine in accordance with claim 4 in which said elements also have portions adapted to retain the thread of an intercepted needle thread loop out of the path of the descending needle as said elements are engaging and transporting the said underlooper thread triangle base line to its position on the other side of the needle path.

7. A sewing machine in accordance with claim 4 in which said elements also have portions adapted to assist a needle thread loop intercepted by the underlooper to pass along said underlooper as said underlooper moves in the direction of interception and as said elements move in the opposite direction.

8. A sewing machine in accordance with claim 7 in which said elements also have portions adapted to retain the thread of an intercepted needle thread loop out of the path of the descending needle as said elements are engaging and transporting the said underlooper thread triangle base line to its position on the other side of the needle path.

9. A sewing machine in accordance with claim 4 in which means are provided for preventing the descending needle from attacking the thread leading to a previously formed and intercepted needle thread loop comprising sequentially complementary means on said underlooper and on said elements; the means on said underlooper being adapted to retard the movement of the intercepted needle thread loop along the underlooper; one means on one of said elements adapted to overcome the retarding effect of the means on the underlooper and to assist the intercepted needle thread loop to pass along the underlooper as the underlooper moves in the direction of interception and as said elements move in one of their directions; and as said elements move in their opposite direction, additional means on the other of said elements effective to retain the intercepted needle thread loop out of the path of the descending needle as said underlooper moves to shed the intercepted needle thread loop, after said needle thread loop is free of the movement retarding means on said underlooper.

10. A sewing machine in accordance with claim 9 in which the movement retarding means on said underlooper 12 comprises a raised projection over which the needle. thread loop must pass to be shed from said underlooper, and the portions on said elements comprise separate edges thereon adapted to en age the thread of the intercepted needle thread loop in sequence as said elements move in opposite directions.

ll. A presentor member for use in a two thread chainstitch sewing machine having a threaded needle which moves on an ascending and descending path to form needle thread loops, a bi-directionally moving threaded underlooper which intercepts said needle thread loops and in which the needle subsequently intercepts the underlooper thread, in sequence, to form chainstitching, and in which said presentor cooperates in the formation of the chainstitching and moves on a bi-directional path transverse to the path of the underlooper; said presentor having a pair of spaced limbs between which the needle may move on its path to intercept the underlooper thread; one of said limbs having a horizontally disposed edge adapted to enga ,e the thread leading to a needle thread loop after interception by the underlooper to assist said intercepted needle thread loop to pass along the body of the underlooper as the presentor moves in one direction; and another horizontally disposed edge adapted to intercept and retain thereon the underlooper thread as said presentor moves in its otherdirection; and the other of said limbs having a horizontally disposed edge adapted to progressively engage and retain said intercepted needle thread loop out of the path of the descending needle and to en age and retain the underlooper thread on said limb to form with the portion of the underlooper thread retained on the first limb, the base line of an underlooper thread triangle, as said presentor moves in its second direction to present said intercepted underlooper thread to the descending needle for interception thereby.

12. In a sewing machine having a threaded needle which moves on an ascending and descending path to form needle thread loops, an oscillating thread carrying underlooper which intercepts said needle thread loops and the thread of which in turn is formed into a triangle for entry therein by said needle; and a bidirectionally moving member having two horizontally disposed and spaced limbs, one limb being disposed to the right and the other limb being disposed to the left of the needle path, each of said limbs having an inner and an outer edge with reference to said needle path; said needle, underlooper and member being arranged to interact so that the thread of a needle thread loop intercepted by said underlooper is caused to pass along said underlooper by the inner edge of the right limb of said member as said underlooper and said member are each moving in one of their respective directions; and so that the outer edge of the right limb of said member engages the thread carried by said underlooper as said underlooper and said member are each moving in the other of their respective directions to form the base line of said thread triangle;

and so that both of said limbs transport said thread base line beyond the path of said needle for entry into said triangle by said needle as it descends and as said member continues to move in its second direction; and so that the thread of the needle thread loop previously intercepted by said underlooper is retained out of the path of the descending needle by the outer edge of the left limb of said member and so that the base line of underlooper thread on said limbs is caused to urge the thread of said needle to form its loop on the opposite side of said needle as said member moves in the first of. its directions to cause said thread base line to come into contact with the thread of said needle as said needle is ascending.

13. In a modified sewing machine having an ascending and descending threaded needle for forming thread loops in the work, a bedplate, a rotating shaft beneath said bedplate, and a box depending from the undersurface of said bedplate, said box containing drive means for said shaft:

' a pivotally mounted member supported beneath said bedplate operatively connected to said shaft for bidirectional movement along the line or" stitching; a support bracket mounted to said box, an arm pivotally mounted on said support bracket; a threaded underlooper carried by said arm; means connecting with the drive means in said box for moving said arm to rock said underlooper transversely to the movement of said member for intercepting the needle thread loops; said member cooperating with said needle and said underlooper and arranged to engage the thread carried by said underlooper to form the base line of a thread triangle disposed transversely to the line of stitching and to transport said thread base line bodily for interception by said needle on its descent, said member having separate means for sequentially shifting a needle thread loop intercepted by said underlooper along the latter and for subsequently retaining the thread lead ing to said needle thread loop out of the path of the needle as it descends to intercept the underlooper thread triangle.

14. A sewing machine in accordance with claim 13 in which the means for moving said pivotally mounted member comprises an eccentric mounted on said shaft, an arm pivotally mounted on the undersurface of said bedplate which carries said member, and a drive link connecting said eccentric and said arm.

15. A sewing machine in accordance with claim 14 in which a demountable bushing is supported on the undersurface of said bedplate; a bracket supported by said bushing; said arm which carries said member being pivotally mounted on said bracket; and a takeup mechanism for the underlooper thread comprising a bent arm pierced with a pair of thread holes in register, supported by said bracket; and a thread manipulating lever attached to said arm, disposed between said thread holes.

16. Mechanism for providing a threaded underlooper for intercepting needle thread loops for use in the conversion for two thread chainstitching of a modified sewing machine having a reciprocating threaded needle which forms needle thread loops, a bedplate, a rotating shaft mounted beneath said bedplate; a pivotally mounted forked member operated from said shaft adapted to cooperate with said needle and an underlooper to form the base line of an underlooper thread triangle and to bodily transport and present said thread base line to the needle for interception thereby; and a box on the undersurface of said bedplate containing drive means for said shaft, closed off at the bottom by a removable cover plate: said mechanism comprising a support member mountable on the bottom of said box in place of said cover plate, an underlooper carrying arm pi'votally supported on said support member, a threaded underlooper carried by said arm, operating means carried by said support member connectible to said drive means in said box when said support member is mounted to said box; means for converting rotary motion to rocking motion connected to said operating means on said support member, and means connecting said underlooper carrying arm to said motion converting means to rock the latter in relationship to movement of said needle and of said member.

17. Mechanism in accordance with claim 16 in which said support member has an extension projecting toward the region of needle reciprocation when said support member is mounted to the bottom of said box; a boss on said extension; said underlooper carrying arm being pivotally mounted in said boss.

18. Mechanism in accordance with claim 17 in which said extension has a branch projecting transversely to the length of said extension; said branch being adaptable for supporting said pivotally mounted forked member thereon.

19. In a sewing machine for producing compound seams including an overedge seam and a spaced two thread chainstitch seam; a plurality of threaded needles, an overedge looper cooperating with one of said needles; an underlocper having two separate thread carrying limbs,

one thread carrying limb adapted to coact with one of said needles and said overedge looper in the formation of the overedge seam and the second thread carrying limb adapted to coact with another of said needles; and an element adapted to intercept and retain the thread of said second limb and positioned to move across the line of passage of said limb at one side of the path of its coacting needle, another element adapted to intercept and retain the same thread and positioned to move across said line of passage at the opposite side of said needle path to form the base line of the chainstitch thread triangle, and operating means for moving said elements and the underlooper thread base line retained thereon across said line of passage to the side of said needle path opposite said line of passage to complete the formation of said thread triangle.

20. In a sewing machine for producing compound seams including an overedge seam and a spaced two thread chainstitch seam; a plurality of threaded needles; an overedge looper cooperating with one of said needles; a common oscillating underlooper carrier; one thread carrying underlooper supported by said carrier coacting with one or said needles and said overedge looper in the formation of the overedge seam; a second thread carrying underlooper supoprted by said carrier coacting with another of said needles; a presentor member cooperating with the second underlooper and its related needle in the formation of the two thread chainstitching, mechanism for moving said presentor on a bi-directional path intercepting the paths of movement of said second underlooper and its related needle; said presenter having a pair of spaced limbs which are disposed at either side of the path of movement of said related needle, said limbs being adapted to intercept the thread of the second underlooper to form the base line of the chainstitch thread triangle as the presenter moves in one direction, said limbs having portions adapted to retain said base line of thread to transport it bodily from one side to the other side of the path of movement of said related needle for interception by said needle.

21. In a sewing machine for producing compound seams including an overedge seam and a spaced two thread chainstitch seam; a plurality of threaded needles moving on an ascending and descending path to form needle thread loops; an overedge looper cooperating with one of said needles; a bidirectionally moving underlooper having two separate thread carrying limbs, one thread carrying limb adapted to coact with one of said needles to intercept its thread loops and to cooperate with said overedge looper in the formation of the overedge seam and a second thread carrying limb adapted to coact with another of said needles to intercept and a member cooperating with said thread carrying limb and its coacting needle in the formation of two thread chainstitching; said member being mounted for movement along the line of stitching; means for moving said member along the line of stitching; means on said member for engaging the thread carried by said second limb to tform a thread triangle for entry by the said coacting needle, with the base line of said thread triangle extending transversely of the line of stitching and for holding said thread base line on said member to bodily transport the thread base line from a position at the rear of the needle path to the front of the needle path as said member is moved along the line of stitching from the rear to the front of the needle path.

22. A sewing machine in accordance with claim 21 in which said bidirectionally moving member has fork shaped sections, one of said sections being adapted to retain the thread of a needle thread loop intercepted by said second limb out of the path of the descending needle as said member is engaging and transporting the thread base line to its position on the other side of the path of the needles.

23. A sewing machine in accordance with claim 21 in which means are provided for preventing the needle which 155 coaetsl with said second limb from attacking the thread leading to a previously formed and intercepted needle thread loop as said needle descends, said means comprising sequentially complementary means on said second limb and on said member; the means on said second limb being adapted to retard the movement of the intercepted needle thread loop along the second limb; one means on said member being adapted to overcome the retarding effect of the means on the second limb and to assist the needle thread loop intercepted by the latter to pass along said second limb as the latter moves in the direction of interception, and as said member moves in one of its directions; and as said member moves in its opposite direction, additional means on said member effective to retain the intercepted needle thread loop out of the path of said needle as said second limb moves to shed the intercepted 165 needle thread loop, after said needle thread loop is free of the movement retarding means on said second limb.

References Cited in the file of this patent UNlTED STATES PATENTS 677,422 Onderdonk July 2, 190 726,311) Klem-m Apr. 28, 1903 1,335,374 Gatohell Mar. 30, 1920 1,528,499 Maffatt Mar. 3, 1925 1,551,996 McCann Sept. 1, 1925 2,389,112 Newton Nov. 13, 1945 2,439,332 Becker Apr. 6, 1948 2,973,730 Schweda et al Mar. 7, 1961 FOREIGN PATENTS 779,133 Great Britain July 17, 1957 

1. IN A TWO THREAD CHAINSTITCH SEWING MACHINE HAVING A THREADED NEEDLE WHICH MOVES ON AN ASCENDING AND DESCENDING PATH TO FORM NEEDLE THREAD LOOPS, A BI-DIRECTIONALLY MOVING THREADED UNDERLOOPER WHICH INTERCEPTS SAID NEEDLE THREAD LOOPS AND IN WHICH THE NEEDLE SUBSEQUENTLY INTERCEPTS THE UNDERLOOPER THREAD, IN SEQUENCE, TO FORM CHAINSTITCHING AND OPERATING MECHANISM FOR MOVING SAID NEEDLE AND UNDERLOOPER ON THEIR RESPECTIVE PATHS; THE COMBINATION WITH A PRESENTOR MEMBER COOPERATING WITH SAID NEEDLE AND SAID UNDERLOOPER IN THE FORMATION OF CHAINSTITCHING, MECHANISM ASSOCIATED WITH SAID NEEDLE AND UNDERLOOPER OPERATING MECHANISM FOR MOVING SAID PRESENTOR ON A BI-DIRECTIONAL PATH WHICH INTERCEPTS THE PATHS OF MOVEMENT OF SAID NEEDLE AND SAID UNDERLOOPER, SAID PRESENTOR HAVING A PAIR OF SPACED LIMBS WHICH ARE DISPOSED AT EITHER SIDE OF THE PATH OF MOVEMENT OF THE NEEDLE, SAID LIMBS BEING ADAPTED TO INTERCEPT THE UNDERLOOPER THREAD TO FORM THE BASE LINE OF A THREAD TRIANGLE AS SAID PRESENTOR MOVES IN ONE DIRECTION, SAID LIMBS HAVING PORTION ADAPTED TO RETAIN SAID BASE LINE OF UNDERLOOPER THREAD TO TRANSPORT THE LATTER BODILY FROM ONE SIDE OF THE PATH OF NEEDLE MOVEMENT TO THE OTHER FOR INTERCEPTION BY THE DESCENDING NEEDLE. 